Flexible strap wrench

ABSTRACT

A strap wrench for grasping and rotating articles, such as cylindrical spin-on filters, comprises a support, a cam member rotatably mounted in the support and a flexible strap having one end attached to the cam member and a second end threaded therethrough. An arcuate surface is formed on the support to abut and substantially conform to outer cylindrical surface portions of the rotated article. Such arcuate surface cooperates with the strap to grasp the article, upon rotation of the cam member, to uniformly distribute a torquing force therearound and to prevent damage thereto.

United States Patent 91 Brantley [111 3,728,916 [451 Apr. 24, 1973FLEXIBLE STRAP WRENCH [75] lnventor: Jerry K. Brantley, Pekin, Ill.

[73] Assignee: Caterpillar Tractor Co., Peoria, 111.

[22] Filed: June 14, 1971 [21] Appl. No.: 152,515

[52] US. Cl ..81/64 [51] Int. Cl. ..B25b 13/52 [58] Field of Search 8H64, 3.43, 68

[56] References Cited UNITED STATES PATENTS 2,995,965 8/1961 Hockney81/64 2,058,949 10/1936 BOrOWSki... .....81/64 X 3,376,628 4/1968 Kyser..81/64 X 2,897,705 8/1959 Rozmus ..81/68 X 3,465,622 9/1969 Winans..81/64 FOREIGN PATENTS OR APPLICATIONS 61,235 6/1948 Netherlands ..8l/3.43

Primary Examiner-Granville Y. Custer, .lr. Assistant ExaminerRoscoe V.Parker Att0rneyCharles M. Fryer et a].

[5 7] ABSTRACT A strap wrench for grasping and rotating articles, suchas cylindrical spin-on filters, comprises a support, a cam memberrotatably mounted in the support and a flexible strap having one endattached to the cam member and a second end threaded therethrough. Anarcuate surface is formed on the support to abut and substantiallyconform to outer cylindrical surface portions of the rotated article.Such arcuate surface cooperates with the strap to grasp the article,upon rotation of the cam member, to uniformly distribute a torquingforce therearound and to prevent damage thereto.

5 Claims, 4 Drawing Figures PATENTEDAPR 24 I975 INVENTOR JERRY K.BRANTLEY BY v 2 j A'ITORNEYS FLEXIBLE STRAP WRENCH BACKGROUND OF THEINVENTION Numerous types of strap wrenches are employed for removingspin-on oil and fuel filters from internal combustion engines. Suchwrenches exhibit disadvantages, such as their inability to uniformlydistribute a torquing force fully around a filter to expeditiously andeasily remove or install same. In addition, the wrenches oftentimescrush or otherwise damage the filter upon rotation thereof due to thefilters thin-wall shell construction.

Damage to the filters shell during removal thereof may be sufficientlysevere to prevent the wrench from gripping the filter. In suchinstances, the service man normally drives a bar or heavy screwdriverthrough the filter and cranks same to break it loose. This procedure isinconvenient, time-consuming and allows uncontrolled escape of fuel oroil.

During installation, replacement filters are customarily tightened byhand, without the aid of a strap wrench, to alleviate the damage andrelated problems. However, since the filters are subjected to severevibrations or pulsations during engine operation, they have a tendencyto loosen to thus induce oil or fuel leakage. The problem isparticularly apparent with respect to filters employed in connectionwith high-performance, fuel injection pumps. Such pumps produce highintensity pressure waves which are transmitted through the filter toinduce loosening thereof. Loosening of the fuel filter presents anespecially dangerous situation due to the fire hazard involved.

SUMMARY AND OBJECTS OF THIS INVENTION An object of this invention is toovercome the above described problems by providing an economical andefficient strap wrench adapted to expeditiously grasp and rotatecylindrical articles, such as spin-on filters, without causing damagethereto. The strap wrench comprises a support having a cam memberrotatably mounted thereon and a flexible strap having one end attachedto the cam member. The support has an arcuate surface formed on a basethereof which substantially conforms to the periphery of the article.The cam member, when rotated, cooperates with the strap to uniformlydistribute a torquing force around the article and to prevent damagethereto.

BRIEF DESCRIPTION OF THE DRAWINGS Further objects of this invention willbecome apparent from the following description and accompanying drawingswherein:

FIG. 1 is a top plan view of a flexible strap wrench embodiment of thepresent invention;

FIG. 2 is a side elevational view ofthe strap wrench;

FIG. 3 is a sectional view of the strap wrench, but il- Iustrating thewrench as it would appear during the installation ofa spin-onreplacement filter; and

FIG. 4 is a view similar to FIG. 3, but illustrating the strap wrench asit would appear during the removal ofa spent filter.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, theillustrated strap wrench embodiment essentially comprises a support 10,having a cam member 11 rotatably mounted therein, and a flexible strap12 attached at one end thereof to the cam member. The U-shaped support(FIG. 2) comprises spaced upstanding legs 13 and 14, secured together bymeans of an intermediate base plate 15. The plate defines an arcuatesurface 16 thereon, subscribed by a radius having its center at point Xin FIG. 1, which faces away from the support and in general concaverelationship thereto.

Since the outer diameters of a series of filters will vary in size,arcuate surface 16 preferably corresponds to the largest filter diameterin the series for which the wrench is to be used. The full accommodationof the largest diameter provides for a slight deflection of the shell ofthe smaller filters, without damage, so that they will assume the shapeof arcuate surface 16. Arcuate surface 16 thus provides for theservicing of a wide range of filter sizes, while yet assuring maximumpossible surface contact between the arcuate surface and the filters.

The contact area provided by the strap wrench of this invention issubstantially larger than the contact areas which are occasioned byconventional strap wrenches. In particular, arcuate surface 16cooperates with strap 12 to substantially fully circumvent anddistribute a torquing force around the filter whereas prior artconstructions normally concentrate high torquing forces at small areason the filter. In FIG. 1, angle a defining the arcuate surface ispreferably selected from the approximate range of from 30 to e.g. 65 asshown.

Cam member 11 comprises a pair of laterally spaced cylindrical bearingportions 17 and 18 rotatably mounted in bores formed in legs 13 and 14,respectively. Snap rings 19 and 20 are suitably positioned in annulargrooves formed on the cam member to prevent axial movement thereof. Thebearing portions are connected together by an intermediate cam means 21which is offset radially with respect to a central rotational axis Y ofthe cam member.

An elongated pin 22 is secured to legs 17 and 18 of the cam member toattach the looped and stitched first end of flexible strap 12 thereto.It should be noted that the pin is offset with respect to axis Y andpreferably diametrically opposed with respect to cam means 21 to providea slot therebetween adapted to receive a second, free end of the straptherethrough.

The strap preferably comprises an elongated, flat band constructed of aflexible and durable woven fabric such as nylon. The strap has a hightensile strength, but yet exhibits sufficient flexibility to envelopeand frictionally grasp the exterior surface of a cylindrical article,such as a spin-on filter F illustrated in FIGS. 3 and 4.

Referring to FIG. 3, the strap wrench is shown in its operative positionfor installing a spin-on filter F. Initially, the workman positionsarcuate surface 16 in abutting relationship with the filter. The freeend of strap 12 is then manually threaded through the slot definedbetween cam means 21 and pin 22 (FIG. 1) and semi-tightened. A squaresocket 23 is formed in each of bearing portions 17 and 18 of the cammember to accommodate a mating torquing tool.

Upon clockwise rotation of the tool and cam member about axis Y in FIG.3,cam means 21 and pin 22 will rotate, as shown, to shorten theeffective length of the strap portions forming a circular continuationof arcuate surface 16. Once the filter is grasped snuggly, the entirestrap wrench is moved clockwise about axis X to tighten the filter apredetermined amount.

FIG. 4 illustrates the removal of a spent filter F by reversing theabove described sequence of operation. In particular, cam member 11 isrotated in a counterclockwise direction to shorten the strap and tograsp the filter by applying a substantially uniform torquing forcetherearound.

What is claimed is:

1. A strap wrench for grasping and rotating cylindrical articlescomprising a support including means defining a substantial arcuatesurface thereon, facing away from said support in general concaverelationship thereto, generally conforming to the outer diameter of anarticle to be rotated,

a cam member rotatably mounted about a central axis thereof in saidsupport, including cam means,

and

an elongated flexible strap having an end attached to said cam membersaid cam means and the position whereat said strap is attached to saidcam member being spaced on said cam member to define a slot therebetweenadapted to receive a second, free end of said strap therethrough.

2. The invention of claim 1 wherein said cam means and the positionwhereat said strap is attached to said cam member are diametricallyopposed on said cam member on respective sides of the central axisthereof.

3. The invention of claim 1 wherein said support is U'shaped to comprisea base defining said arcuate surface thereon and spaced legs having saidcam member rotatably mounted therein.

4. The invention of claim 3 wherein said cam member comprises spaced,cylindrical bearing portions each rotatably mounted in a respective oneof said legs and means for preventing axial movement of said cam memberrelative to said central axis and said support.

5. The invention of claim 1 wherein said arcuate surface is defined byan angle selected from the approximate range of from 30 to

1. A strap wrench for grasping and rotating cylindrical articlescomprising a support including means defining a substantial arcuatesurface thereon, facing away from said support in general concaverelationship thereto, generally conforming to the outer diameter of anarticle to be rotated, a cam member rotatably mounted about a centralaxis thereof in said support, including cam means, and an elongatedflexible strap having an end attached to said cam member said cam meansand the position whereat said strap is attached to said cam member beingspaced on said cam member to define a slot therebetween adapted toreceive a second, free end of said strap therethrough.
 2. The inventionof claim 1 wherein said cam means and the position whereat said strap isattached to said cam member are diametrically opposed on said cam memberon respective sides of the central axis thereof.
 3. The invention ofclaim 1 wherein said support is U-shaped to comprise a base definingsaid arcuate surface thereon and spaced legs having said cam memberrotatably mounted therein.
 4. The invention of claim 3 wherein said cammember comprises spaced, cylindrical bearing portions each rotatablymounted in a respective one of said legs and means for preventing axialmovement of said cam member relative to said central axis and saidsupport.
 5. The invention of claim 1 wherein said arcuate surface isdefined by an angle selected from the approximate range of from 30* to90*.